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The majority of viruses force hosts to do their bidding by regular DNA to RNA transcription. There are, however, other types of viruses called RNA viruses that follow a slightly different method. RNA viruses such as polio, are made up of messenger RNA instead of the regular DNA. They skip the step of incorporating their genetic material into the cell's DNA. Instead, they pretend they are part of the cell's regular messenger RNA and directly pass messages to other parts of the cell to start making viruses.
Usually, viruses follow this method:
- Incorporate DNA into cell's DNA
- DNA makes messenger RNA
- Messenger RNA directs the rest of the cell to make viruses.
However, RNA viruses skips some steps:
- Messenger RNA directs the rest of the cell to make viruses.
Another type of RNA viruses called retroviruses are only able to take control of these cells in reverse. Retroviruses contain a shorthand code of directions coded on RNA strands. For these viruses to be able to replicate and produce protein, they have to convert RNA messages to DNA. Retroviruses contain a special enzyme called reverse transciptase, which allows this process to take place. Once the coded messages are translated into DNA, the virus' message is incorporated directly into the cell's genetic code.
Retroviruses follow these steps:
- RNA changes to DNA
- DNA is incorporated into cell's DNA
- DNA makes messenger RNA
- Messenger RNA directs the rest of the cell to make viruses.
HIV, the virus that causes AIDS, is one of the better known retroviruses. Some scientists theorize that RNA viruses are the cause of cancer. Although it is not yet proven, this solution would explain how the form and function of cancerous cells are affected.
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